In recent years, various types of semiconductor laser devices have been widely used as light sources for optical disc devices. In particular, high power semiconductor laser devices are used as write-use light sources for writing on discs of DVD (Digital Versatile Disc) players, DVD-RAM (Random Access Memory) drives, and the like, and there is a strong demand for higher power and further downsizing of semiconductor laser devices.
A frame type semiconductor laser device, which is one of conventional semiconductor laser devices, is described in JP 2005-311147 A (Patent Literature 1).
FIG. 7 shows a plan view of the frame type semiconductor laser device.
The frame type semiconductor laser device includes a metallic lead frame 102, a plurality of leads 103 to serve as electrodes, and a holding portion 107 for integrally holding the lead frame 102 and the plurality of leads 103.
The lead frame 102 has an element mounting portion 102a, a lead portion 102b and tie bar portions 102c. A semiconductor laser element 101 is mounted on the element mounting portion 102a via a submount member 108. Then, the semiconductor laser element 101 is electrically connected to the electrode leads 103 by wire.
A bottom surface of the element mounting portion 102a is exposed from the holding portion 107, while the tie bar portions 102c extend from the mounting portion 102a. Thus, during operation of the semiconductor laser element 101, the mounting portion 102a and the tie bar portions 102c work for heat radiation, making the heat radiation area enlarged, so that heat radiation characteristics of the semiconductor laser device can be improved.
However, the frame type semiconductor laser device has the following problem. When the semiconductor laser element 101 is enhanced for higher power, there arises a need for enlarging the heat radiation area of the semiconductor laser device for improvement of the heat radiation characteristics. This makes it difficult to downsize the semiconductor laser device.
Also in the frame type semiconductor laser device, when the semiconductor laser device is downsized, there is a problem that a power decline of the semiconductor laser element is inevitably involved to maintain its heat radiation characteristics.